When I towed my trailer with my Express to Iowa in August, was careful in choosing stations. I did discover that the cheapest stations along I-80 were more difficult to access. We took 2 days to drive out, and unhitched at night. I filled while unhitched, so I only needed to fuel 2 times with the trailer. There is a truck stop on I-80 that looked large enough, but they have parking at both ends of the pumps. I will never stop there with a trailer again, even though they were $.15 cheaper a gallon.
On my return, I stayed off the interstates, and fueled in multiple towns were I saw that I could get in and out. Price was not the concern.